IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0285596
(2008-10-09)
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등록번호 |
US-8291719
(2012-10-23)
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발명자
/ 주소 |
- Cowans, William W.
- Zubillaga, Glenn W.
- Cowans, Kenneth W.
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출원인 / 주소 |
|
대리인 / 주소 |
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인용정보 |
피인용 횟수 :
1 인용 특허 :
20 |
초록
▼
A system for improving the thermal efficiency of a thermal control loop in which refrigerant after compression and condensation is applied to an evaporator employs a subsidiary counter-current heat exchange intercepting refrigerant flow to maintain the quality of the refrigerant by exchanging therma
A system for improving the thermal efficiency of a thermal control loop in which refrigerant after compression and condensation is applied to an evaporator employs a subsidiary counter-current heat exchange intercepting refrigerant flow to maintain the quality of the refrigerant by exchanging thermal energy between the input flow and the output flow from the evaporator. The same principle is effective, with particular advantage when small connections have to be made, in systems using mixed phase media and using the concept of direct energy transfer with saturated fluid.
대표청구항
▼
1. A temperature control system employing a two-phase refrigerant and a compressor/condenser loop having an input and output for circulating refrigerant at a controllable temperature to and from a load evaporator having input and output terminals and a known thermal capacity, the temperature control
1. A temperature control system employing a two-phase refrigerant and a compressor/condenser loop having an input and output for circulating refrigerant at a controllable temperature to and from a load evaporator having input and output terminals and a known thermal capacity, the temperature control system including a subsidiary heat exchange loop for enhancing the performance of the system by advantageously utilizing the different thermal energy transfer properties of the two phases of the refrigerant, comprising: a subsidiary heat exchanger coupled between the flow from the output of the compressor/condenser loop to the load evaporator input, the subsidiary heat exchanger having a smaller thermal capacity than the known thermal capacity of the load evaporator, said subsidiary heat exchanger having a first flow path including an input receiving flow from the compressor/condenser loop and an output therefrom coupled to the load evaporator input, and the subsidiary heat exchanger also including a second flow path in counterflow thermal exchange relation along the length of the first flow path, the second flow path including an input receiving flow from the load evaporator output and providing an output flow coupled back to the input to the compressor/condenser loop,at least one temperature-modifying device in series circuit with the input to the first flow path and prior to the subsidiary heat exchanger for lowering the temperature of the flow output therefrom that is input to the load evaporator and increasing the bulk density of the flow therefrom to the evaporator, whereby although the proportion of liquid in the refrigerant mix fed to the load evaporator is partially reduced, the bulk density of the mass moving through the load evaporator is thereby increased to minimize heat transfer losses in the low efficiency region of the load evaporator, andwherein the subsidiary heat exchanger is configured to transfer thermal energy between the two flow paths therein such that the refrigerant flowing in the second path is returned to the compressor/condenser loop in gaseous state. 2. A system as set forth in claim 1 above, wherein the at least one temperature-modifying device comprises a thermo-expansion device in the first flow path prior to the subsidiary heat exchanger, the thermo-expansion device including and being responsive to a pressure sensing device responsive to the pressure in the input line to the compressor and wherein the system further comprises a pressure dropping device in the first flow path subsequent to the subsidiary heat exchanger and prior to the evaporator, said pressure-dropping device introducing a pressure differential driving the counterflows of fluid in the first and second flow paths through the subsidiary heat exchanger. 3. A system as set forth in claim 2 above, wherein the system further comprises a subsystem in the compressor/condenser loop for providing a combined flow at controllable temperature to the evaporator, said subsystem including a first direct flow control for providing a selected proportion of hot gas flow from the compressor and a second derivative flow control for providing a selectively expanded and cooled flow from the condenser, subject to the proportion provided by the first direct flow control and a mixing circuit receiving the first and second flows for providing a combined flow therefrom to the evaporator via the subsidiary heat exchanger. 4. In a thermal control system using the different thermal transfer characteristics of the phases of a two-phase refrigerant and including a refrigeration loop of operative elements incorporating a compressor, a condenser, and an expansion device in sequence, the refrigeration loop being in thermal communication with an evaporator comprising the load to be cooled, the evaporator having a nonlinear heat transfer coefficient in response to localized refrigerant quality variations, wherein quality is expressed in terms of the proportion of vapor mass to total mass, the improvement comprising a subsidiary heat exchange loop disposed between the expansion device and the evaporator and including a counter-current heat exchanger coupling the expansion device to the evaporator on one side and the output from the evaporator to the compressor on the other side, the loop further including a differential pressure device in the coupling between the counter-current heat exchanger output and the evaporator input selected to lower the temperature of flow to the evaporator to a degree approximating the difference between the evaporating refrigerant and the load being cooled, the loop also including a pressure sensing device responsive to the pressure in the output line from the counter-current heat exchanger to the compressor input, and controlling the operation of the differential pressure device in the refrigeration loop. 5. A combination as set forth in claim 4 above, wherein the refrigeration loop comprises a thermo-expansion device including a vapor confining sensing bulb responsive to the temperature of the refrigerant being returned to the compressor from the heat exchanger, the sensing bulb having an internal fluid selected to have a chosen vapor pressure to approximate that of the refrigerant used in the cooling cycle. 6. A system as set forth in claim 4 above, wherein the differential pressure device in the coupling between the counter-current heat exchanger output and the evaporator input is selected to provide a temperature change approximating the superheat of the evaporator. 7. A thermal control system as set forth in claim 4 above, wherein the refrigeration system includes a system for mixing refrigerant media in expanded at least partially vapor phase after condensation and the same refrigerant in pressurized gas phase, including a mechanism for mixing the two different phases for application to the evaporator of given thermal capacity, wherein the subsidiary heat exchange loop is disposed between the mixing mechanism and the evaporator. 8. A system as set forth in claim 7 above, wherein the pressurized gas phase has substantially greater energy content that the expanded vapor phase and wherein the subsidiary heat exchange loop stabilizes the entire thermal control system for effecting relatively small incremental temperature changes. 9. In a compression/condensation temperature control system using a two-phase refrigerant for controlling the temperature of a load evaporator of a known thermal capacity by combining high pressure hot gas flow from a source modulated at a selectable flow rate with a derivative remainder flow from the source that is cooled to a vapor/fluid condensate of the refrigerant, the improvement comprising: a command source varying the hot gas flow, and thereby the derivative flow, prior to the combination thereof;a counter-current flow heat exchanger having a first flow path coupling the combined flow to the load evaporator and having a second, counter-current, flow path coupling the flow from the load back to the compression/condensation system, said heat exchanger having a lesser thermal capacity relative to that of the load evaporator, anda device in the first flow path between the heat exchanger and the load evaporator for lowering the pressure of the combined flow delivered to the evaporator by a selected amount, to assure circulation through the load evaporator and back to the compression/condensation system while maintaining the quality of the two-phase refrigerant in a selected range above zero. 10. A thermal control system using a refrigerant flowing in direct contact with a thermal load having a known thermal capacity whose temperature is to be controlled, comprising: a source of a thermal medium having a two-phase characteristic and a liquid/gas transition within a chosen operative temperature and pressure range applicable to the system;a compressor receiving the thermal medium and providing a compressed gas output at a first elevated temperature and first elevated pressure;a first flow control receiving the compressed gas output and providing a first variable mass flow at an elevated temperature;a medium condenser receiving that portion of the compressed gas output remaining when the first variable mass flow is provided from the first flow control and a liquid pressurized output is provided from the portion remaining at a second lower temperature level;a second flow control comprising an externally stabilized expansion device receiving the liquid pressurized output from the medium condenser and providing the second flow as a selectively cooled expanded output at a reduced pressure;a controller coupled to operate the first flow control for establishing a selected proportional relationship between the first and second flows of the thermal medium;a mixing circuit receiving the first and second flows and providing a combined output to the load;a subsidiary heat exchanger having counter-flowing paths, a first of said paths receiving the combined output from the mixing circuit and being between the second flow control and the load, and the second of said paths receiving the return flow from the load and being between the load and the medium compressor, said subsidiary heat exchanger having a lower thermal capacity relative to the known thermal capacity of the load, anda pressure dropping valve between said subsidiary heat exchanger and the load to reduce the pressure and temperature of the flow that is applied to the thermal load being controlled. 11. In a temperature control system employing a two-phase refrigerant and a compressor/condenser series in a loop also including an expansion valve for cooling the refrigerant to provide a cooled expanded two-phase flow to a load evaporator in the loop, the improvement comprising: a subsidiary counter-flow heat exchanger in the loop between the compressor/condenser series and the load evaporator, said subsidiary heat exchanger passing input flow in the two-phase state from the compressor/condenser series to the load evaporator on a first side, and passing return flow in two-phase state from the load evaporator on the second side, the thermal capacity of said subsidiary heat exchanger being less than the thermal capacity of the load evaporator;a temperature dropping device in the input path on the first side of the subsidiary heat exchanger for insuring a temperature differential between the two sides sufficient to insure flow of refrigerant and transfer of thermal energy through the evaporator and to reduce heat transfer losses in the load evaporator by reducing the rate at which the two-phase refrigerant converts to vapor; andwherein the expansion valve is coupled into the first side path prior to the subsidiary heat exchanger and the temperature dropping device comprises a pressure dropping valve coupled in the first side path between the subsidiary heat exchanger and the load evaporator and introducing a temperature drop approximating the difference between the evaporating refrigerant and the load being cooled. 12. A temperature control system improvement as set forth in claim 11 above, wherein the expansion valve is a thermo-expansion valve including a sensor responsive to the temperature in the second path output from the subsidiary heat exchanger.
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